Just as a reminder, you can set a CLASSPATH to point to directories, but the only classes that will be found are the "loose" (.class) files. JARs have to be mentioned explicitly by name.
Systems like Tomcat make that not obvious, because their startup scripts often have code in them that scoop up all the jars in a directory and add each on to the CLASSPATH. The
java compiler ("javac") and "java" programs don't.
In Tomcat 4, the servlet defs were in %TOMCAT_HOME%\common\lib\servlet.jar. Where you set TOMCAT_HOME is your privilege.